Reinforced-concrete building construction.



J. KAHN.

REINFORCED CONCRETE BUILDING CUNSI'RQCHCN'. APPLICATION FILED N0 4.191a.

1,285,211 1 I Iu'urnml Nov. 1S], 1913,

JULIUS KAHN, 0F YOUNGSTOWN, OHIO.

. REINFORCED-CONCRETE BUILDING CONSTRUCTION.

as? an.

specification of Letters Patent. Patented NOV. 19, 1918.

Application filed November 4, 1916. Serial No. 129.417.

ar anged in the slabs and wherein the sire s are more evenlydistrilrited from the slabs into the tops of the columns thanheretofore. The nature of the invention will be pointed out later, butto facilitate the understanding thereof three features of decidedimportance may he noted at the out.- scl: (i) The stresses aretransmitted from the slabs into a column head of a horizontalcross-section considerably greater than the cross-section of the columnproper by a main reinforcement consisting of bars which liesubstantially parallel to and are spaced,

from each other in the head, said bars passing entirely across thelatter from side to side and extending therefrom into the slabs ondiverging lines; (2) the angular distribution and the length of the barsis made to correspond to the stresses which are to be carried to theheads; (3) an auxiliary rein? forcement consisting of two intersectingsets of bars arranged parallel to the center lines of the columns andproperly spaced from each other throughout a zone of considerablewidthcis employed.

In the drawings, which show a preferred embodiment of the invention,Figure 1 is a plan view of one floor panel ith enough of thesin-rounding panels to illustrate the general arrangement of thereinforcement. Fig. 2 is a section on the line 2-2 of Fig. 1. Fig. is anenlarged section corresponding to the right hand portion of Fig. 2.

The reinforced concrete columns 1 of suitable construction are locatedat the corners of a floor panel 2( preferably square or rectangular) andare provided with flaring heads 3 that may be shaped, if desired, formdropped panels 4. Passing acres upper portions of column heads {whichmay be regarded as extending to the upper surface of the door) on linesparallel to the center lines joining adjacent columns are two sct-s'ofcautaliver or top bars, each Set lying in a single horizontal plane andhaving its members spaced apart from one another. The reinforcement, incrossing the, column heads, therefore occupies very little depth and maybe most advantageously placed with reference to the transmission ofstress. It, will be observed that each set of bars includes therelatively short bars 5 and the relatively long bars 6 and 8, and thatthe end portions of these bars diverge from one another substantiallyfrom the periphery of the head of the corresponding column, the angleswhich the end portions make with the adjacent edges of the head beingsubstantially equal. The bars 6, after passing over the column head, dipdownwardly into the lower portion of the slab and preferably extend ashort distance into the head of the adjacent column; the bars. 8 ofsimilar contour, but, preferably of less length, terminate in the slabon either side of the center lines of columns; while the ends of theshort bars 5 preferably lie wholly in the upper portion of the slab andextend outwardly beyond the inflection points. Thus the bars 6 resistnegative bending moments over the column heads as well as positivemoments midway between the columns and substantially on the lines of thecolumn centers at the sides of the rectangular panels, and the bars 8have a like function with respect to the positive stresses in the panelsat points somewhat farther removed from the corresponding center line ofcolumns. The bars 5 take negative bending moments in the slabs in thevicinity of the inflection points and also resist the negative momentsover the column heads. It Will be-noticed that the bars 6 and 8 for agiven column cross the correspondinghars for the adjacent columns atsubstantially the mid-point of the span. The bars 5, 6 and 8 constituteWhat may be termed the main reinforce ment.

Besides the main reinforcement there is used an auxiliaryreinforcementconsisting of two sets of spaced beam or bottom bars 9, thebars of each set for a given panel'being parallel and crossing those ofthe other set in the central portion of the panel, it being understoodthat, in this vicinity, they lie near the lower face of the slab to takepositive bending moments. As the auxiliary bars approach the linesjoining the edges of the column heads. they rise up into the upper faceof the slab, and preferably pass en-

